Abstract

The presence of side eects in even a very simple language of expressions gives rise to a number of semantic questions. The issue of evaluation order becomes a crucial one and, unless a specic order is enforced, the language becomes non-deterministic. In this paper we study the denotational semantics of such a language under a variety of possible evaluation strategies, from simpler to more complex, concluding with unspecied evaluation order, unspecied order of side eects and the mechanism of sequence points that is particular to the ANSI C programming language. In doing so, we adopt a dialect of Haskell as a metalanguage, instead of mathematical notation, and use monads and monad transformers to improve modularity. In this way, only small modications are required for each transition. The result is a better understanding of dierent evaluation strategies and a unied way of specifying their semantics. Furthermore, a signicant step is achieved towards a complete and accurate semant...

Citations